Compression release for internal combustion engines



Sept. 26, 1967 D. E. wr-:GLAGE ETAL 3,343,525

COMPRESSION RELEASE FOR INTERNAL COMBUSTION ENGINES Filed May 4, 1966 FIGI 7a Ih FIG-2 F IG-Sl INVENTORS DAV/D E. lA/ELRGE BY ALBERT H. WEGLHGE United States Patent O 3,343,525 COMPRESSION RELEASE FR INTERNAL COMBUSTION ENGINES David E. Weglage and Albert A. Weglage, Dayton, Ohio, assignors of one-third to Walter Becker, Dayton, Ohio Filed May 4, 1966, Ser. No. 547,503 9 Claims. (Cl. 12.3-182) 'The present invention relates to internal combustion engines and, more specifically, concerns the manual starting of-such engines.

The manual starting of internal combustion engines, particularly those used in connection with garden and horticultural implements such as lawn mowers, snow blowers, pumps and the like has been quite some problem and, therefore, various attempts have been made to facilitate the manual starting of such engines by releasing the compression during the starting of the respective engine.

Most of the heretofore known so-called compression release devices designed lfor facilitating purely manual starting of internal combustion engines are either based on a permanent change of the carn controlling the inlet or outlet valve or on the employment of an auxiliary cam for controlling the respective valve. The permanent change in the cam contour is such that the respective valve is during the compression stroke held open longer than normally and thus represents a permanent loss of compression. In order to maintain this loss within permanent limits, the permanent change in the cam contour of this known arrangement is such as to cause a rather slight compression release movement only of the valve and to this end requires Very close tolerances. If these tolerances are not met, the said device is practically inefficient. The arrangements employing an auxiliary cam have this cam designed similar to the rst mentioned cam so that the respective valve will be held open longer than normally, 'and rely on centrifugal Iforce to make the auxiliary cam ineffective and to permit the normal cam to control the valve. While this last mentioned device avoids permanent loss of `compression during the ordinary running operation of the engine, it is rather expensive in view of the elements involved. The auxiliary cam, however, must likewise be so designed as to permit the valve to close during one revolution of the cam. In other words, the auxiliary cam fundamentally works in the same way as in the compression release device with permanently modified cam contour and thus has the very same drawback with regard to the limitations concerning the possible compression release during the starting operation. In our co-pending application Ser. No. 480,086 led Aug. 16, 1965, now Patent No. 3,307,527 there has been disclosed a compression release mechanism which in contrast to the above identied compression release devices is completely independent of the contour of the valve controlling cams and thus is completely independent of the cams with regard to the extent to which the respective valve for purposes of compression release may be held open. Moreover, the compression release device set forth in our said co-pending application employs a new principle for making the compression release ineffective during the normal running of the engine, namely by using for this purpose the gaseous ow from the crankcase to the spring chamber occurring during the operation of the engine. It is `an object of the present invention further to simplify the compression release device set forth in our above mentioned co-pending application so as to` be able to avoid any line tolerances with regard to any elements used in the compression release system itself.

It is a further object of this invention to provide an improved compression release device in which the elements involved are of an extremely simple structural ice nature thereby avoiding any costly and complicated dies while permitting an extremely low cost manufacture.

Still another object of this invention consists in the provision of a compression release `device as set forth in the two preceding paragraphs, which can easily be installed, even in older engines.

These and other objects and advantages of the invention will appear more clearly from the following speciiication in connection with the accompanying drawings, in which:

FIG. 1 is a vertical section through a customary one cylinder four stroke cycle internal combustion engine arranged horizontally, as it is used for various purposes, `for `instance horticultural equipment, said engine being shown equipped with a compression release arrangement according to the present invention while the section through the portion provided with said compression release device is taken along the line I-I of FIG. 2.

FIG. 2 is a section along the line II-II of FIG. 1.

FIG. 3 represents a section taken along the line III-III of FIG. 2.

FIG. 4 illustrates an exploded view of the compression release mechanism proper.

FIG. 5 shows a slight modification of the compression release shown in FIG. l inasmuch as the compression release lever has one of its arms bent differently for application in a vertical engine.

The present invention is characterized primarily by a cranked lever, preferably a cranked wire, pivotally journalled in the spring chamber of the engine between the valve stems or push rods of the inlet and outlet valves and having one arm extending into the passage through which during the operation of the engine customarily passes the gaseous ow from the crankcase into the spring chamber from where said gaseous ilow is released e.g. to the atmosphere. The crank of the said lever is adapted to move into and out of the path of the spring dish means of one of the valves.

Referring specifically to the drawing, the internal combustion engine illustrated therein which may be of the general type shown in FIG. 1 of our co-pending application Serial No. 480,086 above referred to, is shown in FIG. 1 by way of example as a horizontal engine. The internal combustion engine shown in the drawing comprises a cylinder block 1 with a cylinder 1a. Mounted on cylinder block 1, in customary manner, is a cylinder head lb. Cylinder block 1 comprises a spring chamber 2 which has connected thereto a housing or crankcase 3. Journalled in said housing 3 is a cam shaft 4 which is drivingly connected to the crank shaft (not shown) of the engine in a manner customary with four-stroke cycle internal combustion engines through gears. As is also well known in the art, the cylinder 2 has reciprocably mounted therein a piston (not shown) which is drivingly connected to the crank shaft.

Likewise in 'customary manner, cam shaft 4 is provided with a rst cam 5, and a second cam 6. Cam 5 normally, i.e. during the ordinary driving operation of the engine, is in continuous engagement with a lifter 7 having a lifter shank 7a which in turn engages the stem 8 of the exhaust valve 9 controlling the connection of the engine cylinder with an exhaust port (not shown) through a passage 1c. As will be seen from FIG. 1, that portion of valve stem 8 which extends into spring chamber 2 is surrounded by a valve spring 10 having one end resting against spring chamber wall 11. The other end of spring 10 rests against a spring keeper 12 holding spring 10 under preload and being held in its position on one hand by spring 10 and on the other hand by a C-clamp 13 (see also FIG. 4) which ,rests in a recess 14 of spring keeper 12 and engages a groove 8a in valve stern 8. As will be 3 evident from the above, spring continuously urges valve 9, shown in an open pressure releasingposition, into its closing position. Cylinder block 1 furthermore, in customary manner, comprises a lifter controlled vby cam 6 on cam shaft 4. Cam 6 in turn through lifter shank 15a and valve shank 16 controls the inlet valve 17 which latter controls a passage 17a communicating with a fuelsupply passage 17b. Similar to the outlet valve 9,

also the inlet valve 17 is provided with a spring 18 lo-V ers, the spring chamber 2 communicates with the interior of the housing or crankcase 3 through a passage 21 through which during the operation of the engine a gaseous ilow occurs from the crankcase to the spring chamber 2 from where it is released, e.g. through a breather plate Aof any standard design for instance of the type shown in FIGS. 12 and 12a of our above mentioned co-pending application Ser. No. 489,086.

While the diameter of said passage 21 may vary with various designs, in conformity with the requirement for yreleasing the gaseous ow from the crankcase 3 and passagek 21 into the spring chamber 2 and from there e.g. through the breather device into the atmosphere, it is to be noted that no change in the diameter of the piston and the said passage 21 of the standard engine is necessary for the present invention, and that this will not change the principle of the present invention. As a matter of fact, it is Very easy to equip any standard four-stroke cycle internal combustion engine later with a pressure release device according to the present invention regardless of the size of the piston and the said passage 21.

The arrangement described so far is substantially standard with four-stroke cycle engines as they are employed for instance withr rotary lawn mowers with the exception of the specific shape of spring keeper 12.

As will be seen from FIGS. 1 and 4, spring keeper 12 has a fairly long hub 12a which engages valve stem 8 with slide tso as to be properly guided therein. That side of spring keeper 12 which faces away from spring wall chamber 11 is provided with a recess 14 which receives the C-clamp 13 against which rests one end of a small preloaded spring 22 which in the position shown in FIG. 1 surrounds valve stem 8 and lifter shank 7a. That end of spring 22 which is remote from spring keeper 12 rests on a plate 23 (FIGS. 1, 2 and 4). The said plate 23 is provided with two bores 24 and 25 through which lifter shanks 7a and 15a respectively pass with slide t.

In addition thereto, plate 23 is provided with a third bore 26. That side of plate 23 which rests on the bottom wall 27 of spring chamber 2 is provided with a transverse groove 28 which preferably has a slightly rounded bottom for a purpose which will presently appear. As will be seen best from FIGS. l and 3, a cranked compression release lever 29 in the form of a Wire has two relatively short arms 30 and 31 journalled in the transverse bore 28 of plate 23, and since spring 22 and a similar spring 32 (the latter being arranged Ibetween plate 23 and spring keeper 19) rmly hold plate 23 against bottom wall 27 of spring chamber 2, the arms 30 and 31 of compression release lever 29 are rmly pivotally journalled in groove 28.

As will furthermore be seen from FIGS. 1 and 3, compression release lever 29 has a cranked portion 33 which extends through bore 26 and can move therein from the full line position shown in FIG. 1 to the dash line position shown in FIG. 1 and vice versa. Compression release lever 29 furthermore has an arm 34 With a rst section 34a and a second section 34b (see FIG. 4) which latter is bent with regard to arm section 34a. While the angle between arm sections 34a and 34b as shown in FIG. 1

4 is approximately it is to be understood that this angle can greatly vary and may e.g. be as will appear more clearly from theY operation. The main pointis that section 34a must be long enough to pass through bore 26 and that arm section 34b will when in its dashline position occupy such a location that the cranked portion 33 has moved over to such an extent away from the axis of stem 8 and shank 7a as to permit spring 10 to push valve stem 8 and lifter shank 7a in the direction toward cam 5 so that lifter 7 will at all times be in engagement with cam 5. Furthermore, the center of gravity of lever 29 must be so located that lever 29, when not held in its dash-line position willV by gravity move into its full-line position as soon as spring keeper 12 has moved sufiiciently toward the left with regard to FIG. 1. From the above, it will also be clear that arm section V34b is :bent with regard to arm section 34a-somewhat in the direction in which the air owing toward bore 26 will tilt .lever arm section 34b to move the cranked section 33 into its ineffective position.

Operation It may be assumed that the engine a portion of whichV is shown in FIG. 1 and which by way of example is assumed to be a single cylinder lawn mower engine with horizontally extending lifter and valve shanks, is at a standstill. In this position, the compression release or control lever 29 is in its solid position shown in FIG. l which represents its effective or compression releasing position. In this position, the crank portion 33 of said compression release lever keeps the spring keeper in raised position to such an extent that the valve 9 occupies its compression releasing position shown in FIG. l, while the lifter 7 is disengaged from cam 5 due to the fact that Vin view of the compression release lever 29 being in its effective position, spring 10 does not cause valve stem 8 to push lifter 7 into engagement with cam 5, which lifter 7 due to its horizontal position does not by itself slide back into engagement with cam 5. Merely by way of example, the valve 9 may in its compression releasing position be open by .060. However, it should be noted that this value is given merely by way of example and that, if desired, this opening can be even greater.

When the crank shaft is now manually turned for starting the engine, for instance by means of a pulley connected to the crank shaft and a rope extending around the pulley, as is standard in numerous lawn mower engines, the immediate movement of the piston and of the crank shaft quickly creates a gaseous ow from the crankcase to the .spring chamber 2 through bore 21. Spring chamber 2 is vented :by means of a spring chamber above referred to. On its way from the crankcase through bore 21 into spring chamber 2, the said gaseous flow impinges upon the lever section 34b and moves the same in counterclockwise direction as soon as cam 5 by its higher cam face 5a lifts lifter 7 and thereby valve 9 beyond its opening position shown in FIG. 1 and thus also lifts spring keeper 12 so that the cranked portion 33 of lever 29 can move into its dash line position, i.e. away from valve stem 8 and lifter shank 77a.Y The momentum which thev movable components of the engine gain during the initial starting phase in view of the fact that valve 9 at the very start of the starting operation was held relatively wide open by the compression release lever 29 is fully suicient to move the piston through its next following cornpression stroke, and as a rule the engine will re. This means that the engine will operate at an even higher speed, and the said gaseous flow through passage 35 will be more than suincient to hold lever 29 in its effective position.

However, if the engine should not fire, the speed of the engine will immediately decrease and, consequently, the said gaseous How-through passage 35 will drop to such an extent that the lever 29 will by its own weight assumek the position in FIG. 1 as soon as during the upward stroke of lifter 7 the cranked portion 33 is free to move below spring keeper 12 in which instance the solid position of control lever 29 is restored and a new starting operation of the engine can be effected with the compression release fully effective as before. Similarly, when after running the engine for a period of time, the latter is turned off, shortly before the engine comes to a standstill, the said gaseous flow from the crankcase to the spring cham- -ber decreases to such an extent that the control lever will move back to its effective position as outlined above. In this way, the compression release is always effective when the engine is to be started. Similarly, the compression release remains ineffective throughout the normal operation ofthe engine including its idling phase so that there will be absolutely no compression loss during the normal operation of the engine, and the engine will operate as if there were no compression release at all present.

For the sake of completeness, it may be mentioned lthat according to the specific showing in FIG. l, the compression release lever extends into a channel 35 which is formed in many standard engines as a reinforcement for the crankcase and by a reinforcement of the spring bottom portions through which the valve Shanks extend. However, for the function of the compression release according to the present invention, this passage is not necessary since as soon as the above mentioned gaseous ow from the crankcase to the spring chamber Ithrough bore 21 has built up, it impinges upon the compression :release lever in the manner outlined above.

It will also be evident from the above, that the total length of the two lever sections 34a and 34b should be such that the lever 29 will by gravity always tend to occupy the position shown in solid lines in FIG. 1. Furthermore, the angle between the sections 34a and 34b, as mentioned above is not limited to the specitic angle shown in the drawing but may vary to a considerable extent. The main point is that the air can pass between the spring chamber bottom wall 27 and the section 3417 so as to tilt lever 19 in the above outlined manner.

Modification of FIG.

The arrangement of FIG. 5 substantially corresponds to that of FIG. l with the exception that the compression release lever 29b is bent in the opposite direction with regard to lever 29 inasmuch as the compression release mechanism shown in FIG. 5 is applied to an upright engine. The various elements appearing in FIG. 5 and corresponding to those of FIG. 1 therefore have been designated with the same reference numerals as in FIG. l. Also the operation of the compression release mechanism shown in FIG. 5 is the same as that described in connec- -tion with FIGS. l to 4. In other words, when the higher cam face of cam 5 lifts lifter 7, while the said gaseous iiow from the crankcase 3 through passage 21 into spring chamber 2 occurs, the said gaseous ow impinging upon the compression release lever 29b will move the same in counter clockwise direction and thereby pull the crank from below spring keeper 12 from its full line position into its dash position shown in FIG. 5 as soon as the spring keeper is suiiiciently lifted by cam 5 and lifter 7. On the other hand, when the engine after a running period slows down in order to come to a stop, lever 2911 will -by gravity be moved from its dash line position into its full line position with the crank 33b below spring keeper 12. While in FIG. 5 the lever section 3411 has its end resting on the bottom wall of passage 35a, it will be understood that this is not necessary, and that the full line position of lever 29b could also be arrested by the crank 33h hitting the edge of the hole through which it extends. Similar remarks also apply incidentally to lever 29 in FIG. 1 with regard to its dash line position.

It is furthermore to be noted that while the compression release arrangement according to the present invention has been described as being applied to the exhaust valve, it can also without any change be applied instead to Ithe intake valve because the compression release opening is so great that an accidental explosion in the cylinder will be impossible, while, on the other hand the compression release mechanism according to this invention operates so, as has been explained above, that if the intake valve is -controlled thereby, the intake valve will close ahead ofthe time at which the ignition occurs.

It is, of course, to he understood that the present invention is, by no means, limited to the specific embodiments shown in the drawings but also comprises any modifications within the scope of the appended claims.

What we claim is:

l1. An internal combustion engine having a cylinder block with spring chamber means, a crankcase connected to said cylinder block, a crank shaft rotatably journalled in said crankcase, conduit means establishing communication between the interior of said crankcase and the interior of said spring chamber means for conveying a gaseous ow occurring during the operation of said engine from said crankcase into said spring chamber means, and means for venting said spring chamber means, which includes: inlet and outlet valve means controlled by said crank shaft, each of said valve means being movable into a closing and opening position and vice versa and having a valve stem extending into said spring chamber means, lifter means operable by said crank shaft and extending into said spring chamber means for cooperation with said valve stems, spring keeper means respectively surrounding and being supported -by said valve stems, preloaded spring means operatively connected to said `spring keeper means and continuously urging said valve means to move to their closing positions, cranked lever means pivotally journalled about an axis spaced from the aXes of said lifter means and including a cranked portion located within said spring chamber means and movable into the path of movement of one of said spring keeper means to prevent the latter and thereby the valve stem carrying the same from completing its normal stroke toward the lifter means cooperating therewith whereby the respective valve means remains open, said cranked portion also being movable out of the path of movement of said one spring keeper means to thereby permit the latter and thus the valve means pertaining thereto to move into its closing position in conformity with the movement of said cam shaft, said lever means having arm means extending through said conduit means into said crank case into the path of the gaseous flow passing from said crankcase through said conduit means into said spring chamber means during the operation of said engine, said lever means being so designed and journalled as to be continuously urged by gravity to move into the path of movement of said one spring keeper means and also being movable by the said gaseous ow from said crankcase t0 said spring chamber means at least at engine idling speed and above the same in a direction opposite to the lever movement by gravity against the force of gravity acting upon said lever means.

2. An internal combustion engine according to claim 1, in which said crank arm means is formed by a wire.

3. An internal combustion engine according to claim 1, which includes plate means provided with an opening permitting the movement therein and passage therethrough of said cranked portion of said lever means, said plate means being mounted on that wall portion of said spring chamber means which defines one end of said conduit means, that surface of said plate means which faces said last mentioned wall portion being provided with groove means extending along a diameter line of said opening and journalling said lever means.

4. An internal combustion engine according to claim 3, in which said plate means is slidably engaged by said lifter means, and preloaded spring means interposed between said one spring keeper means and said plate means to hold the latter substantially stationary.

5. An internal combustion engine according to claim 1,

in which said one spring keeper means has a relatively long hub portion engaging the valve stem surrounded ,thereby with slide t to thereby prevent said one spring keeper means `from tilting toward the axis of the valve stem surrounded thereby.

6. An internal combustion engine according to claim 3, in which .said lever means has two aligned arms pivotally journalled in said groove means and also has two additional arms forming an obtuse angle with each other, one of said additional arms extending through said conduit means into said crankcase while the-other one of said additional arms is located in said crankcase outside said conduit means.

7. A compression release unit for installation in an internal combustion engine having a crankcase, spring chamber means, reciprocable valve stem means in said spring chamber means, spring keeper means on said valve stem means, and conduit means leading from said crankcase into said spring chamber means, said compression release unit comprising: plate means for mounting on that wall portion of said spring chamber means which defines one end of said conduit means, said plate means having an opening therethrough and having that surface which when said unit is installed will face said Wall portion of said spring chamber means provided with groove means eX- tending along a diameter line of said opening, cranked lever means adapted to be journalled in said groove means and provided with a cranked portion for extension through said opening and also being provided with arm means for extension through said conduit means into said crankcase,

said lever means whenw journalled`in'said groove means having the tendency by gravity to occupy a rst position and when installed into an internal combustion engine being movable to -a second position by a gaseous blow passing from said crankcase through said conduit means into said spring chamber means during the operation of the engine.

8. A compression release unit according to claim 7, in which said plate means is provided With openings for slidably receiving said valve stem means.

9. A compression release unit according to claim 7, in which said lever means is formed by a wire of round cross section and in which the arm means'of said lever means which are adapted to extend through said conduit means into said crankcase include two sections forming an obtuse angle with each other.

References Cited UNITED STATES PATENTS 854,035 5/ 1907 Hansen-Ellenhammer 123-182 2,323,304 7/ 1943 Bowman 123-182 v 3,307,527 3/ 1967 Weglage 123-182 FOREIGN PATENTS 376,490 7/ 1932 Great Britain.

CARLTON R. CROYLE, Primary Examiner.

RALPH D. BLAKESLEE, Examiner. 

7. A COMPRESSION RELEASE UNIT FOR INSTALLATION IN AN INTERMINAL COMBUSTION ENGINE HAVING A CRANKCASE, SPRING CHAMBER MEANS, RECIPROCABLE VALVE STEM MEANS IN SAID SPRING CHAMBER MEANS, SPRING KEEPER MEANS ON SAID VALVE STEM MEANS, AND CONDUIT MEANS LEADING FROM SAID CRANKCASE INTO SAID SPRING CHAMBER MEANS, SAID COMPRESSION RELEASE UNIT COMPRISING: PLATE MEANS FOR MOUNTING ON THAT WALL PORTION OF SAID SPRING CHAMBER MEANS WHICH DEFINES ONE END OF SAID CONDUIT MEANS, SAID PLATE MEANS HAVING AN OPENING THERETHROUGH AND HAVING THAT SURFACE WHICH WHEN SAID UNIT IS INSTALLED WILL FACE SAID WALL PORTION OF SAID SPRING CHAMBER MEANS PROVIDED WITH GROOVE MEANS EXTENDING ALONG A DIAMETER LINE OF SAID OPENING, CRANKED LEVER MEANS ADAPTED TO BE JOURNALLED IN SAID GROOVE MEANS AND PROVIDED WITH A CRANKED PORTION FOR EXTENSION THROUGH SAID OPENING AND ALSO BEING PROVIDED WITH ARM MEANS FOR EXTENSION THROUGH SAID CONDUIT MEANS INTO SAID CRANKCASE, SAID LEVER MEANS WHEN JOURNALLED IN SAID GROOVE MEANS HAVING THE TENDENCY BY GRAVITY TO OCCUPY A FIRST POSITION AND WHEN INSTALLED INTO AN INTERNAL COMBUSTION ENGINE BEING MOVABLE TO SAID CRANKCASE THROUGH SAID SAID CONDUIT MEANS INTO SAID SPRING CHAMBER MEANS DURING THE OPERATION OF THE ENGINE. 